this article makes BLE (bluetooth low energy) seem pretty attractive compared to ZigBee; BLE is said to have lower power requirements (it lists current draw for RF4CE but not for ZigBee, but it says that RF4CE is similar to ZigBee; RF4CE current draw is said to be too high for a CR2032 battery), better range, and better resistance to jamming; and BLE is said to be able to do mesh networking with the addition of an application)